Plugging my thread i started yesterday, first: http://www.escapistmagazine.com/forums/read/18.301354-My-feet-hurt-after-that-dance-ADwD-Spoilers#12017863
Now, OT: Pretty sure Jon's alive, or at least will be brought back as a R'hllor zombie. Other major characters have been killed off, yes, but it's always served a purpose. Jon's death doesn't seem to serve any purpose, and in fact seems counter-productive to the whole narrative.
Brienne is definitely leading Jaime into a trap... assuming she's not dead already. We still don't know that her shouted word actually saved her, especially considering how psychotic Catelyn/Stoneheart is.
It took me a lot of thinking to figure out how Arya pulled off that hit, too, but i believe the key is the fact that she noted the insurer always bit the coins when he took them (standard practice to be sure they're not fake). So... i'd guess the coin was coated with an ingested poison.
I loved the book, but seriously the cliffhangers in this one are ridiculous--by far the worst cliffhangers in the series. None of the battles that seemed to be imminent from the beginning of this book were resolved by the end (most notably Winterfell and Meereen). And of course the status of Jon's life or death...